1. Field of the Invention
This invention relates to a combination fiber optic raceway and water hose for use in remote control of an underground mining machine.
2. Description of the Prior Art
Remote control systems for use in underground mining machines have developed in recent years to better ensure safety of operating personnel by permitting operation of mining machines at a point remote from the mine face where unsupported roof and ribs can be an immediate hazard. Similarly, redundant remote control systems are being utilized to provide backup in the event of a failure of the primary remote control system. The backup or secondary remote control system gives some assurance that personnel will not be exposed to danger present at the face in order to manually recover the miner or repair the primary remote control system. On such fiber optic redundant remote control system is disclosed in U.S. Pat. No. 5,110,189.
It is also known to practitioners in the art to include the remote control cable, typically carrying a low energy electrical signal, within the three-phase power trailing cable electrical supply source to the miner. U.S. Pat. No. 4,884,847 discloses the use of a fiber optic cable for transmitting communication signals from a remote location to a mining machine.
Since the electrical signals have previously been the practically exclusive method for providing remote control through the trailing cable, it has been impracticable to place the control cable within the water supply hose. The proximity to water and its inherent conductive electrical properties would invite unreasonable risks of fault currents and system failures. However, with the advent of fiber optic technology these risks are eliminated.
Most, if not all, mining machines are provided with water supply means when mining coal, for dust control, fire suppression and other reasons. A flexible water hose is used to connect the fixed pipe water supply to the continuous miner water distribution system. Normally, means is provided to protect the water supply hose from being broken, as when the moving treads run over the hose. In practice it is more frequently encountered that the mining machine will run over its power trailing cable than it will pierce its water supply hose.
Fiber optic cable technology is not readily adaptable to field splicing in the environment of coal mines. A relatively clean and dry area which is well illuminated is required to align the fine fibers and join them using an epoxy. While it is known to remotely control the operation of electrical equipment in an underground mine by a fiber optic control system, the known devices expose the fiber optic cable to damage and interruption of the transmitted communication signal.
Also, measures must be taken to protect the integrity of the fiber optic cable and not subject it to undue stress as encountered when tension is applied to the cable, as occurs when it is stretched. To allow for efficient conveyance of the cable to the power equipment and permit the cable to move with the power equipment, the cable must be supplied from a source, as from a spooling device or the like. Known spooling devices for cables are well known as disclosed in the following U.S. Pat. Nos. 1,384,153; 1,940,701; 1,904,702; 4,174,816 and 5,117,859 as well as U.K. Patent No. 2,152,476, Canadian Patent No. 538,927 and German Patent No. 2720159. However, with a fiber optic cable reeling and unreeling the cable from a rotating spool exposes the internal optic fibers to damaging stresses. Therefore, there is need to provide method and apparatus for efficiently protecting the fiber optic cable from damage.